A comparative in vitro study on fluoride release and water sorption of different flowable esthetic restorative materials

Study on the mechanical and aging properties of an antibacterial composite resin loaded with fluoride-doped nano-zirconia fillers

Preventing the occurrence of secondary caries serves as one of the significant issues in dental clinic, thus make it indispensable to improving the properties of conventional composite resin (CR) by developing a novel CR. In present study, two groups of experimental CRs loaded with different contents of fluoride-doped nano-zirconia fillers (25 wt% and 50 wt%) were fabricated. The surface topography, mechanical performance, fluoride release, antibacterial effect, aging property and cytotoxicity of the experimental CRs were evaluated subsequently. A uniform distribution of the F-zirconia fillers over the whole surface of resin matrix could be observed. The experimental CRs showed continuous fluoride release within 28 days, which was positively correlated with the content of F-zirconia fillers. Moreover, the amount of fluoride release increased in the acidic buffer. Addition of F-zirconia fillers could improve the color stability, wear resistance and microhardness of the experimental CRs, without reducing the flexure strength. Furtherly, the fluoride ions released continuously from the experimental CRs resulted in effective contact and antibacterial properties, while they showed no cytotoxicity. As a consequence, considerations can be made to employ this new kind of composite resin loaded with fluoride-doped nano-zirconia fillers to meet clinical requirements when the antimicrobial benefits are desired.

Highlights on Drug and Ion Release and Recharge Capacity of Antimicrobial Removable Prostheses

This article aimed to review the ion and drug release, recharge abilities, and antimicrobial properties of drug/ion-releasing removable prostheses, and to assess their capability in preventing and inhibiting denture stomatitis as well preventing caries and reversing carious lesions. Data was collected from published scientific papers listed in PubMed database from January 1975 to December 2021. English full-text articles, involving clinical or in vitro studies, focusing on removable prostheses and are concerned with drug/ion release and rechargeability as a way to prevent or inhibit denture stomatitis or dental caries were included. The relevant articles reported that ion- or drug-modified polymethylmethacrylate acts as a reservoir for these ions and drugs and is capable of releasing significant amounts with sustained release effect. Recharging of modified resin resulted in greater sustainability of ion and drug release, thus improving the long-term effects of protection against demineralization and reducing the adhesion of Streptococcus mutans and Candida albicans. Modifications of removable prostheses with rechargeable ions and drugs enhance remineralization, hinder demineralization, and reduce microbial adhesion in difficult-to-access areas. Selection of denture base for clinical use will consider its ability to act as an ion/drug reservoir that is capable of release and recharge.

Comparative Fluoride Ion Release Pre and Postrecharge Situations among Three Different Pediatric Dental Restorative Materials: An In Vitro Study

Objectives

To determine the initial fluoride (F) release and rerelease after recharge of three pediatric dental restorative materials when aged in artificial saliva (M1) and deionized water (M2).

Materials and methods

A total of 30 disks, 10 disks of each restorative material R1: Jen Rainbow, Jen Dent Ukraine; R2: Tetric® N-Flow, Ivoclar Vivadent, and R3: resin-modified glass ionomer cement (RMGIC) (Fuji II LC- GC Corporation) were fabricated and were tested for F dynamics in two different media, M1: artificial saliva, M2: deionized water group. The F initial release was measured on the 1st, 7th, 14th, 21st, and 30th day, and on the 31st day, acidulated phosphate F (APF) gel was applied and F rerelease was measured on the 31st, 37th, 44th, 51st, and 60th day using F ion-specific electrode (Orion). The result was statistically analyzed using two-way analysis of variance (ANOVA) and post hoc Bonferroni test.

Results

Fluoride (F) ion release was significantly higher in deionized water than in artificial saliva (M1), and F ion rerelease (after recharge) was significantly higher in artificial saliva (M1). Fuji-II LC demonstrated a significantly (p < 0.05) higher F release and rerelease among all the tested materials. Among the tested composites, R2: Tetric® N-Flow exhibited significantly higher F dynamics than R1: Jen Rainbow composite.

Conclusion

All the tested restorative materials exhibited optimum F release (0.024 ppm, that is, the range to prevent newer carious lesions) in both the pre and postrecharge conditions. Even though Fuji-II LC demonstrated significantly better F dynamics in the tested scenarios, Tetric® N-Flow has the additional advantage of improved mechanical retentive and esthetic properties along with the optimum F release in pre and postrecharge scenarios.

How to cite this article

Mathias MR, Rathi N, Bendgude VD, et al. Comparative Fluoride Ion Release Pre and Postrecharge Situations among Three Different Pediatric Dental Restorative Materials: An In Vitro Study. Int J Clin Pediatr Dent 2022;15(6):729-735.

COMPARATIVE EVALUATION OF A FISSURE SEALANT AND A FLOWABLE COMPOSITE: A 36-MONTH SPLIT-MOUTH, RANDOMIZED CLINICAL STUDY

OBJECTIVES

The purpose of the present clinical evaluation was to investigate the effect of a fissure sealant and a flowable composite at fissures of permanent molars in terms of retention and caries-incidence rates over a 36-month period.

METHODS

Thirty-four patients, ages varied from 16 to 22 years, diagnosed with at least 2 non-cavitated pit-and-fissure caries in the first and second molars were involved in the study. A total of 220 sealants, were placed in 117 upper molars and 103 lower molars. Teeth were sealed with either a flowable resin composite (Tetric Evo Flow) or a sealant material (Helioseal F)(n=110). Each restoration was evaluated in terms of retention and caries incidence at 6, 12, 24 and 36 months according to their location as well. Data were analyzed using Mann-Whitney U, Friedman and 1-way ANOVA tests at p < 0.05.

RESULTS

Tetric Evo Flow showed total retention with 95.5%, 93.8%, 88.5% and 80.2% at 6, 12, 24 and 36-month follow-ups respectively, while Helioseal F had retention rates of 95.5%, 94.8%, 85.4% and 80.2% respectively. After 36-months, there were 6 subjects totally lost in Helioseal F group, whereas 7 of the Tetric Evo Flow sunjects were totally lost. Caries development was firstly detected at 12-month evaluation for both of the materials however, no significant differences were observed among materials in retention rates or caries incidence after 36-month follow-ups (p>0.05).

SIGNIFICANCE

Using the flowable composite found as effective as the fissure sealant after 36-months regarding retention and caries incidence rates.

Wear Behavior and Surface Quality of Dental Bioactive Ions-Releasing Resins Under Simulated Chewing Conditions

Bioactive materials can reduce caries lesions on the marginal sealed teeth by providing the release of ions, such as calcium, phosphate, fluoride, zinc, magnesium, and strontium. The presence of such ions affects the dissolution balance of hydroxyapatite, nucleation, and epitaxial growth of its crystals. Previous studies mostly focused on the ion-releasing behavior of bioactive materials. Little is known about their wear behavior sealed tooth under mastication. This study aimed to evaluate the wear behavior and surface quality of dental bioactive resins under a simulated chewing model and compare them with a resin without bioactive agents. Three bioactive resins (Activa, BioCoat, and Beautifil Flow-Plus) were investigated. A resin composite without bioactive agents was used as a control group. Each resin was applied to the occlusal surface of extracted molars and subjected to in vitro chewing simulation model. We have assessed the average surface roughness (Ra), maximum high of the profile (Rt), and maximum valley depth (Rv) before and after the chewing simulation model. Vickers hardness and scanning electron microscopy (SEM) also analyzed the final material surface quality). Overall, all groups had increased surface roughness after chewing simulation. SEM analysis revealed a similar pattern among the materials. However, the resin with polymeric microcapsules doped with bioactive agents (BioCoat) showed increased surface roughness parameters. The material with Surface Pre-reacted Glass Ionomer (Beautifil Flow-Plus) showed no differences compared to the control group and improved microhardness. The addition of bioactive agents may influence surface properties, impairing resin composites' functional and biological properties. Future studies are encouraged to analyze bioactive resin composites under high chemical and biological challenges in vitro with pH cycles or in situ models.

Development of New Experimental Dental Enamel Resin Infiltrants-Synthesis and Characterization

The aim of the present study was to obtain experimental infiltration materials, intended for the treatment of dental white spots, and to investigate them. Two series of infiltrants (P1–P6)/(P1F–P6F) were obtained, based on different monomer mixtures, without/with glass filler (with fluoride release ability). Each infiltrant from the second series contained the same amount of glass powder, and each infiltrant from the (P–PF) group contained the same resin composition. The characteristics of the experimental infiltrants were investigated by degree of conversion (DC), mechanical strength, water sorption (WS), and fluoride release, in addition to residual monomer for (P1F–P6F) infiltrants. The results were compared with those obtained for commercial Icon infiltrant. For the experimental infiltrants, without/with filler, the recorded DC was in the range of 58.27–89.70%/60.62–89.99%, compared with Icon (46.94%) 24 h after polymerization. The release of fluoride depends on the permeability of the polymer matrix, with respect to the water sorption, which may help to diffuse ions in the storage medium but which can also influence the release of residual monomers. The highest flexural strengths were recorded for the (TEGDMA/HEMA/Bis-GMA) infiltrants (133.94 ± 16.389 MPa/146.31 ± 7.032 MPa). The best experimental infiltrants were P2 and P2F (Bis-GMA/HEMA/TEGDMA).

Comparative evaluation of Rheological characteristics of Giomers and other Nano-flowable resin composites in vitro

Objective

The purpose of this research was to determine the viscoelastic properties of a group of commercially available nano-flowable resin composites; and to explore the relation between these properties and the materials’ composition (with/without fluoride), filler size description (nano-filled, nanohybrid and submicron-filled) and filler loading (by volume).

Methods

Rheological measurements were performed using a rheometer. A Dynamic frequency sweep test was conducted to evaluate the complex viscosity, storage and loss moduli, loss tangent, and complex shear modulus at an angular frequency (ω) of 0.1–100 rad/s. Comparative evaluations of the nano flowable resin composites on rheological properties was performed, and statistically analyzed using one-way ANOVA.

Results

The results indicated that all the tested materials exhibited shear-thinning flow behaviour. As the shear rate increased, the complex viscosity of the nano-flowable composites decreased. The nanohybrid filled flowable resin composites exhibited the highest complex viscosity, while the nano-filled flowable resin composites exhibited the lowest value. The submicron-filled materials exhibited the lowest complex shear moduli and loss tangent values. Conclusions: The findings from the current study provided comprehensive evaluation of the rheological properties of different nano-flowable composites. The observed differences in rheological properties among the tested materials were independent of their fluoride content or filler size. Furthermore, no relationship was found between the complex viscosity of the tested nano-flowable resin composites and their filler volume.

Surface Characteristics, Fluoride Release and Bond Strength Evaluation of Four Orthodontic Adhesives

Orthodontic adhesives have similar properties in terms of fluoride release, roughness, shear bond strength or cement debris for specific clinical conditions. Three commercial consecrated orthodontic adhesives (Opal Seal^®, Blugloo^®, Light Bond^®) were compared with an experimental orthodontic material (C1). Brackets were bonded to enamel using a self-etch technique followed by adhesive application and then de-bonded 60 days later. Share bond strength evaluation, scanning electron microscopy, atomic force microscopy and fluoride release analysis were performed. The highest amount of daily and cumulative fluoride release was obtained for the experimental material, while the lowest value was observed for Opal Seal^®. The materials evaluated in the current study presented adequate shear bond strength, with the experimental material having a mean value higher than Opal Seal and Blugloo. The atomic force microscopy measurements indicated that the smoothest initial sample is Opal Seal^® followed by Light Bond^®. Scanning electron microscopy evaluation indicated different aspects of cement debris on the enamel and/or bracket surface, according to the type of adhesive. The experimental material C1 presented adequate properties in terms of shear bond strength, fluoride release, roughness and enamel characteristics after de-bonding, compared to the commercial materials. Under these circumstances, it can be considered for clinical testing.

Water Sorption and Solubility of Flowable Giomers

The objective of this study is the characterization of a novel experimental flowable giomer (G) regarding water sorption, water solubility, and the microstructural characteristics, in comparison to three commercial giomers: Beautifil flow Plus X F00 (B-F00), Beautifil flow F02 (B-F02) and Beautifil flow Plus X F03 (B-F03), Shofu, Kyoto, Japan. Methods: Water sorption/solubility was performed by weighing the specimens before and after water immersion for 1, 2, 3, 14, 21 and 30 days. Data analysis was carried out with the software Origin2019b Graphing & Analysis using the ANOVA test and the Tukey test for post hoc comparison of the groups of materials. The microstructural analyses were done with a scanning electron microscope (SEM) and an atomic force microscope (AFM). The results showed significant differences between the tested materials (p < 0.05). For sorption, the Tukey test indicated differences between all four sample groups, except between B-F02 and B-F03, which exhibited no differences in any of the investigation days. The Tukey test also showed significant differences regarding solubility between all sample groups in the 30-day interval. SEM images and roughness showed that after 30 days of immersion in water, the experimental giomer G had the roughest surface.

Preliminary In Vitro Study of Fluoride Release from Selected Ormocer Materials

The purpose of the in vitro study presented in this paper was to determine the long-term release of fluoride ions from selected ormocer materials (Admira (A), Admira Flow (AF), Admira Seal (AS)). The release of fluoride ions from these materials into a saline solution (0.9% NaCl) and deionized water was tested for 14 weeks. In a long-term study the measurements were taken after 1 and 3 h, then 1, 2, and 3 days and then at weekly intervals for 14 weeks. In a short-term study the measurements were made after 3, 24, 48, 72, 69, 168 h, i.e., within 7 days. All materials used in the test showed a constant level of fluoride release. The highest level of cumulative release of fluoride ions into deionized water was found in the AS material (23.95 ± 4.30 μg/mm²), slightly lower in the A material (23.26 ± 4.16 μg/mm²) and the lowest in the AF material (16.79 ± 2.26 μg/mm²). The highest level of cumulative release into saline solution was found in AF (8.08 ± 1.30 μg/mm²), slightly lower in AS (7.36 ± 0.30 μg/mm²) and the lowest in A (6.73 ± 1.10 μg /mm²). After 1 h of immersion of the samples in the saline solution, the highest level of fluoride was released by AF (0.57 ± 0.06 μg/mm²) followed by A (0.20 ± 0.03 μg/mm²) and AS (0.19 ± 0.02 µg/mm²). Moreover, in the 14-week study, the total amount of fluoride release into the saline, which imitates the environment of the oral cavity, was observed as the highest in the AF sample.

Release and Recharge of Fluoride Ions from Acrylic Resin Modified with Bioactive Glass

Background: Oral hygiene is essential for maintaining residual dentition of partial denture wearers. The dental material should positively affect the oral environment. Fluoride-releasing dental materials help to inhibit microbial colonization and formation of plaque as well as to initiate the remineralization process in the early cavity area. Aim: To evaluate fluoride ion release and recharge capacity, sorption, and solubility of polymethyl methacrylate (PMMA) dental resin modified with bioactive glass addition. Materials and methods: Two bioactive glass materials (5 wt% Kavitan, 10 wt% Kavitan, and 10 wt% Fritex) and pure 10 wt% NaF were added to dental acrylic resin. After polymerization of the modified resins, the release levels of fluoride anions were measured based on color complex formation by using a spectrophotometer after 7, 14, 28, and 35 days of storage in distilled water at 37 °C. Subsequently, specimens were brushed with a fluoride-containing tooth paste on each side for 30 s, and the fluoride recharge and release potential was investigated after 1, 7, and 14 days. Sorption and solubility after 7 days of storage in distilled water was also investigated. Results: The acrylic resins with addition of 10% bioactive glass materials released fluoride ions for over 4 weeks (from 0.14 to 2.27 µg/cm²). The amount of fluoride ions released from the PMMA resin with addition of 10 wt% Fritex glass was higher than that from the resin with addition of 10 wt% Kavitan. The acrylic resin containing 10 wt% NaF released a high amount of ions over a period of 1 week (1.58 µg/cm²), but the amount of released ions decreased rapidly after 14 days of storage. For specimens containing 5 wt% Kavitan glass, the ion-releasing capacity also lasted only for 14 days. Fluoride ion rechargeable properties were observed for the PMMA resin modified with addition of 10 wt% Fritex glass. The ion release levels after recharge ranged from 0.32 to 0.48 µg/cm². Sorption values ranged from 10.23 μm/mm³ for unmodified PMMA resin to 12.11 μm/mm³ for specimens modified with 10 wt% Kavitan glass. No significant differences were found regarding solubility levels after 7 days. Conclusions: The addition of 10 wt% Fritex and 10 wt% Kavitan bioactive glass materials to heat-cured acrylic resin may improve its material properties, with bioactive fluoride ion release ability lasting for over 4 weeks. The resin modified with 10 wt% Fritex glass could absorb fluoride ions from the toothpaste solution and then effectively release them. Addition of fluoride releasing fillers have a small effect on sorption and solubility increase of the modified PMMA resin. Clinical significance: The addition of bioactive glass may be promising in the development of the novel bioactive heat-cured denture base resin.

Optical properties and masking capacity of flowable giomers

Background and aims

To assess the color, translucency and masking properties of novel flowable giomers.

Methods

Three flowable giomers were used for the fabrication of 1-mm thick samples (n=126) in three different consistencies (Beautifil flow Plus X F00; Beautifil flow F02; Beautifil flow Plus X F03, Shofu Dental Corporation, Japan) and two shades (VITA Classical shade A2 and A3). The relative spectral reflectance was recorded over white, black, C3 (VITA Classical shade C3 simulating a severe tooth discoloration), and a tested-sample colored background. Lightness (L*), and color coordinates a* and b*, Relative Translucency parameter (RTP₀₀) and masking capacity of C3 background were calculated; differences in color and translucency were compared with thresholds for perceptibility and acceptability (PT and AT). Statistical analyses used significance tests for paired samples.

Results

All tested materials displayed increased values of L*: for A2 F00=86.16(±0.86), F02=86.39(±0.63), F03=86.40(±0.63); for A3: F00=84.24(±0.58), F02=83.34(±0.3), F03=84.19(±0.4), as well as of RTP: for A2 F00=30.34(±0.88), F02=31.37(±0.94), F03=31.11(±1.15), for A3 F00=29.64(±1.64), F02=30.79(±1.02), F03=30.1(±1.26). For A2 samples, the masking capacity was significantly different for all materials, whilst for A3 there were differences only between F00-F03 and F02-F03.

Conclusions

The tested flowable giomers proved high values of lightness and translucency. The color differences between the materials with the same designation and different consistencies were below the perceptibility threshold in most cases. In addition, the differences in relative translucency parameter ranged between the perceptibility and acceptability thresholds. However, all tested flowable giomers had an unacceptable masking capacity for a dyschromic background.

Survival Rates for Porcelain Laminate Veneers: A Systematic Review

The aim of this systematic review was to analyze and compare the most up-to-date information available on long-term, medium-term, and short-term survival rates of porcelain laminate veneers (PLVs) and investigate the homogeneity in current studies or lack of it. An electronic search was performed using PubMed, Ovid MEDLINE, Cochrane Library, Web of Science, EBSCO, Science Direct, Wiley, and Scopus databases. Based on the PRISMA guidelines, the main inclusion criteria consisted of research articles published after the year 2000, in vivo studies with a follow-up period of at least 1 year and reporting of the Kaplan–Meier estimated cumulative survival rates. Quality assessment of the included studies was performed using the modified systematic assessment list consisting of 24 items. Thirty full-text articles were reviewed in detail. A total of 30 articles met the inclusion criteria and were selected for qualitative synthesis. The remaining 27 publications were retained to discuss the heterogeneity in the current literature and reported longevity of veneer restorations. A conclusive estimation of the longevity of PLVS beyond 20 years is lacking. The availability of evidence in the current literature is limited in terms of sample size and duration of follow-up. However, the majority of studies have concluded that PLVs have high-success rates and predictable patient outcomes. The present literature indicates an increased heterogeneity among research study designs. Researchers should aim for homogeneous study designs that can be included in systematic reviews and meta-analyses.

Giomers in dentistry - at the boundary between dental composites and glass-ionomers

Introduction

From the variety of direct restorative dental materials, composite resins are considered as having the most esthetic and functional properties. The conservative preparation, esthetic results, good mechanical qualities and surface finishing properties of dental composites, combined with the protective properties of fluoride from glass-ionomers, led to a new generation of dental materials: the giomers.

Objective

The purpose is to review the available literature about the giomers, regarding the chemical composition, handling properties and esthetics, adhesion and microleakage, fluoride releasing and protection offered, clinical indications.

Method

The search was carried out using ScienceDirect and PubMed databases with the following keywords: giomer, esthetic properties giomers and fluoride releasing giomers. A total of 232 articles were initially selected, with the following inclusion criteria: full text articles, written in English, with topics on the properties and the clinical implications of giomers. Papers presented as abstract were not included. In the next step, review articles, duplicates, and articles in other languages were removed; as a result, a total of 44 sources published between 2004 and 2017 were selected.

Results

The selected articles referred to the following aspects about the giomers: chemical composition (8 articles), adhesion and microleakage (10 articles), fluoride releasing and pulp protection (15 articles), clinical indications (6 articles), effects of additional treatments and dietary habits (11 articles).

Comparative evaluation of fluoride release and recharge potential of novel and traditional fluoride-releasing restorative materials: An in vitro study

Aim

The aim of this study was to evaluate and compare the fluoride ion release and uptake of glass ionomer cement GP IX Extra (GE), EQUIA^® Forte Fil (EF), Beautifil Bulk (BB), Dyract^® XP (DXP), Tetric N-Ceram^® (TNC) in vitro.

Materials and Methods

The restorative materials were divided into five groups (n = 12), namely G1 - GE, G2 - EF, G3 - BB, G4 - DXP, G5 - TNC. Fluoride release was checked using fluoride ion-selective electrode (Orion 9609BNWP, Ionplus Sure-Flow Fluoride, Thermo Scientific, USA) at time intervals of 1 day and thereafter at 3, 7, 14, 21, and 28 days. Following this, fluoride recharge was done with 1.23% acidulated phosphate fluoride gel (12,300 ppm, Pascal International Inc., 2929 Northup Way, Bellevue, USA) after 28 days and each sample was re-checked for fluoride release at the same time intervals.

Statistical Analysis

One-way ANOVA with post hoc Games-Howell test for intergroup and repeated measures ANOVA with post hoc Bonferroni test for intragroup analysis. P < 0.05 was considered statistically significant.

Results

On intergroup analysis, Group 2 showed high values of fluoride release and recharge at all-time intervals which were significantly higher (P < 0.001) than Groups 1, 3, 4 and 5. Intragroup analysis showed significantly higher (P < 0.001) fluoride release and recharge at the end of day 1 which decreased progressively with time for all the tested materials.

Conclusion

EF showed the highest fluoride release and recharge potential across all time intervals compared to other tested restorative materials and the greatest fluoride release was seen on day 1.